Magnetron device



Feb. 18, 1958 P. H. PETERS, JR., ETAL 2 MAGNETRON DEVICE Filed April 26, 1955 /nvenzorzs RSI/1,21 hf P Donald A.

by m qns, Jn; I {bur Unite States Albany, N. Y., assignors to General Electric Company, a corporation of New York Application April 26, 1955, Serial No. 504,050

6 Claims. (31. 315-3913 Our invention relates to improved magnetron devices which are particularly suited for voltage tuning applications.

In our copending application, Serial No. 169,712, filed June 22, 1950, now Patent 2,774,039, entitled Magnetron and Systems Therefor and assigned to the same assignee as this application, we described and claimed a method and apparatus for tuning a magnetron over a substantial frequency range by varying the anode voltage. As pointed out in detail in that application, the conditions existing during operation which are compatible with voltage tuning include a limited supply of electrons in the interaction space so that they may be bunched 'by the relatively weak high frequency fields that may exist and also by relatively heavy and uniform loading throughout the tuning range.

In Hamvas Patent 2,617,956, dated November 11, 1952, is described and claimed a magnetron device of the interdigital type. The device as there described is of simple construction and particularly suited to mass production, utilizing an envelope and base which are standard in the receiving tube industry. Our present invention relates particularly to the provision of a magnetron device which retains the simplicity and adaptability to mass production methods which characterize the device of the aforementioned Hainvas patent but which at the same time provides in operation the conditions required for voltage tuning over a substantial frequency range.

Specifically, we have provided a simple magnetron structure in which the supporting end rings for a cylindrical array of anode segments are provided with circumferentially extending gaps so that in conjunction with a loop having the arms thereof each connected to a different one of the rings on one side of the gaps and a pair of lead-in conductors connected to the rings on the opposite side of the gaps, a closed-end parallel transmission line is formed with the anode segments distributed along its length.

It is an object of our invention to provide a new and improved electric discharge device of the magnetron type.

It is another object of our invention to provide a magnetron device which is of simple and economical construction and which at the same time is well suited to anode voltage tuning applications.

Further objects and advantages of our invention will become apparent as the following description proceeds, reference being had to the accompanying drawing in which Fig. 1 is an enlarged perspective view of a magnetron device embodying our invention, and Fig. 2 represents schematically a development of the anode circuit of the device shown in Fig. l. I

Referring now to the drawing, our invention is shown embodied in an electric discharge device including a generally cylindrical envelope 1 including a header or stem 2 through which a plurality of electrically conductive and relatively stiff lead-in conductors 3-8, inclusive, are sealed. The envelope may to advantage be a standard 7-pin miniaatent fiiice Patented Feb. is, less 2 ture envelope of the type used in radiojreceiving tubes, the 7th lead-in conductor having been omitted in the drawing.

The anode assembly includes agenerally cylindrical array of elongated conductive anode segments 9-16, inelusive, with alternate segments supported respectively from a different one of the annular conductive end rings 17-and 18; As indicated, these rings are supported respectively from lead-in conductors 5 and 8 by means of suitabletabs to whichthe lead-in conductors are welded. End shields 19 and 20 of suitable insulating material are secured respectively to the end rings 17 and 13 by means of tabs 21 formed integrally with the end rings and extending through suitable openings in the insulating discs.

As indicated in the drawing, the anode segments are formed integrally with the rings 17 and 18 and those associated with one ring extend at their free ends through suitable openings formed in the insulating disc supported from the other ring so that the anode members and insulating discs form an assembly which is supported in the envelope by the lead in conductors 5 and 8, connected respectively to the end rings 17 and 13. The discs 19 and 20 are also centrally apertured to receive a cathode sleeve 22 which is supported concentrically with the end rings and the array of anode segments. The sleeve is heated by a suitable resistance heater clement received within the sleeve and having its terminals connected with the leadin conductors 3 and 4. The'cathode sleeve is connected by means of a conducting strap 23 to the lead-in conductor 7. As Visible in the drawing, the electron emission enhancing coating 24 on the cathode sleeve extends over only a portion of the cathode surface. In the particular embodiment illustrated, about /3 of the length of the cathode is coated and by suitable adjustment of the heating current, the total emission available in the interaction space is limited to render the space charge conditions existing during operation compatible with voltage tuning.

In accordance with an important feature of the present invention, the anode structure provides essentially a parallel transmission line enclosed within-the tube and along the conductors of which the interdigital anode segments 946, inclusive, are distributed. As illustrated in the drawing, the end rings 17 and 18 which support the anode segments are provided with gaps 24 and 25 so that they are circumferentially discontinuous, the gaps being provided ne'xt'to adjacent anode segments in the array. A U-shaped conducting loop 26 having arms 27 and 28 connected respectively with the free ends of anode segments 15 and 16 provides the closed end of the transmission line assembly. It will be noted that the lead-in conductors 3 and 8 are connected to the ring members 17 and 18 respectively immediately adjacent the opposite sides of the gaps 24 and 25 with respect to the arms of the U-shaped conductor 26. The magnetic field required in the operation of the device may be provided by a suitably magnetized annular permanent magnet member 29.

Electrically, the structure just described may be better understood by reference to the schematic illustration of Fig. 2 in which the supporting rings 17 and 18 have been shown as straightened out to provide the parallel conductors of the transmission line. In Fig. 2, the parts corresponding to the parts of Fig. l have been designated by the same numerals but these numerals have been primed because of the schematic showing of Fig. 2. It will be noted that the arms 27' and 28' are connected to the ends of the anode segments 15 and 16. In this way, the length of these segments is included in the length of the wires of the transmission line and the length of the loop is in this way effectively increased. It will also be apparent that the vanes 9-16, inclusive, are distributed along the length of the transmission line. As illustrated schematically in Fig. 2, the ends of the lines are extend ed by the lead-in conductors 5 and 8 which extend to the exterior of the envelope. As illustrated, a resistive load 36 is connected across these conductors and may, for example, be provided by a IOO-ohm, /z-watt carbon resistor.

To give an idea of the actual size of one tube constructed in accordance with out invention, the anode diameter is .220 inch, the cathode diameter is .100 inch, and the length of the anode-cathode assembly is .375 inch. The nominal anode voltage is 150 volts and the tuning range extends from 550 to 1100 megacycles with a tuning .rate of about 8 rnegacycles per volt change at the anode voltage.

While we have shown and described a particular embodiment of our invention,.it will be apparent to those skilled in the art that modifications may be made without departing from our invention and we, therefore, aim by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. in a magnetron, the combination comprising a plurality of elongated anode segments arranged in a cylindrical array, a pair of conducting end rings, alternate anode segments being connected at one end thereof to one of said rings and the remaining anode segments be ing connected at the opposite ends thereof to the other of said rings, each of said rings having a gap therein and a generally U-shaped conductor having each arm thereof connected to a different one of said rings adjacent the gap therein.

2. In a magnetron device, the combination comprising a plurality of elongated anode segments arranged in a cylindrical array, a pair of conducting end rings, alternate anode segments being connected at one end thereof to one of said rings and the remaining anode segments being connected at the opposite ends thereof to the other of said rings, each of said rings having a gap therein and a generally U-shaped conductor having each arm thereof connected to a different one of said rings adjacent the gap therein through one of said anode segments.

3. In a magnetron, the combination comprising an envelope, a pair of conducting rings supported in spaced relation within said envelope, a plurality of elongated anode segments arranged in a cylindrical array with alternate anode segments connected to one of said rings and extending toward the other of said rings and with the remaining anode segments connected to said other of said rings and extending toward the first of said rings, each of said rings having a gap therein, a generally U-shaped conductor having each arm thereof connected to a different one of said rings adjacent the gap therein through one of 4 said anode segments and a pair of lead-in conductors connected respectively to said rings on the opposite sides of said gaps.

4. In a magnetron, the combination comprising an envelope, a pair of conducting rings supported in spaced relation within said envelope, a plurality of elongated anode segments arranged in a cylindrical array with alternate anode segments connected to one of said rings and extending toward the other of said rings and with the remaining anode segments connected to said other of said rings and extending toward the first of said rings, each of said rings having a gap therein, a generally U-shaped conductor within said envelope having each arm thereof connected to a different one of said rings adjacent the gap therein and a pair of lead-in conductors connected respectively to said rings on the opposite sides of said gaps.

5. In a magnetron device, the combination comprising an envelope, a pair of conducting rings supported in spaced relation with said envelope, a plurality of elongated anode segments arranged in a cylindrical array with alternate anode segments connected to one of said rings and extending toward the other of said rings and with the remaining anode segments connected to said other of said rings and extending toward the first of said rings, each of said rings having a gap therein, a generally U-shaped conductor having each arm thereof connected to a different one of said rings adjacent the gap therein and a pair of lead-in conductors connected respectively to said rings on the opposite sides of said gaps, whereby said anode segments are distributed along a parallel transmission line including said end rings, said U-shaped conductor and said lead-in conductors.

6. An interdigital rnegnetron comprising an envelope, a pair of conducting rings supported in spaced relation within said envelope, an insulating member supported from each of said rings, a plurality of elongated anode segments arranged in a cylindrical array with alternate anode segments connected to one of said rings and extending through spaced openings in the member supported from the other of said rings and with the remaining anode segments connected to said other of said rings and extending through openings in the insulating member supported from the first of said rings, each of said rings having a gap therein, a generally U-shaped conductor having each arm thereof connected to a different one of said rings adjacent the gap therein through one of said anode segments, a pair of lead-in conductors connected respectively to said rings on the opposite sides of said gaps and an elongated cathode supported from said insulating members in concentric relation with respect to said cylindrical array.

No references cited. 

